Field of Invention
The present invention relates to cooling systems for commercial agricultural vehicles and in particular, but not exclusively, to a cooling unit for a tractor and method of controlling the same.
Description of Related Art
Commercial agricultural vehicles, such as tractors, frequently operate in off-highway environments in which a substantial volume of debris lies on the ground. For example, during crop harvesting, a large volume of waste product is generated by the harvester. This waste falls to the ground behind the harvester. When tractor wheels subsequently pass over the debris it can be thrown into the air and drawn into the tractor's cooling system. This can cause the cooling system to become blocked which can limit the efficiency of the heat exchanger and potentially damage the engine.
The cooling system typically comprises a heat exchanger for removing heat from the engine coolant, a fan for blowing air across the heat exchanger to increase the rate of heat exchange, and a grid positioned upstream of the fan to prevent larger debris from entering the cooling system.
Blockage can occur upstream of the fan at the grid, or downstream of the fan at the heat exchanger.
It is known to monitor the fan motor's current and to reverse the direction of the fan in the event that the current drawn by the motor increases in response to a blocking of the cooling system. However, reversing the fan is only effective at removing debris from the over-pressure side of the cooling package, that is to say, from the grid.
It is an objective of the present invention to at least mitigate one or more of the above problems.